By Michael Knoblauch, Keyland Polymer LLC
Heat-sensitive substrates such as medium
density fiberboard (MDF) and plastics must
have a lower temperature to cure the finish.
UV-curable powder coating is one answer to
coating these types of novel substrates.
UV-curable coating technology
is increasingly being seen as the
future technology in the area of
industrial coatings. The technology
represents one of the rapidly growing
segments in the coatings industry,
and is arguably emerging as the
answer to the rising environmental
concerns and stringent regulations.
Several application-related advantages
come to serve the technology that
include absence of pot life issues,
lower energy costs, fast cure speed,
and reduced environmental impact.
According to Global Industry
Analysts Inc., one-component
UV-curable coating ranks among the
fastest coating chemistries available in
the present context. To cure one-component,
UV-curable coating takes few
seconds to minutes, which makes it
more ideal for use in applications that
require faster turnaround time.
Thermoset or thermally cured
powder coatings were developed in
the 1960s as functional coatings and
have been adapted and developed
for a variety of applications. As those
of us in the industry know, powder
coatings give superior wear resistance,
barrier properties, and cost
effectiveness.
They have no volatile organic
compounds (VOCs) or hazardous air
particulates (HAPs).
The first commercial applications
for UV-curable powder coatings in
the United States began in 1998.
They were an automotive radiator
and an industrial motor.
In 2001, Decorative Veneer built
the first UV-curable powder coating
facility for MDF in Plainwell, Mich.,
and that was followed by Radex in
London, Ont.
Additionally, application facilities
were built in Europe for MDF and
PVC cushion floor. Then in 2005, the
Decorative Veneer system moved to
Cleveland and the company DVUV
formed. Its key markets include
retail, healthcare, education and
office furniture, and specialty applications.
In 2006, Keyland Polymer
Ltd. formed to develop, formulate,
and manufacture UV-curable powder
coatings for DVUV and other
customers.
UV Powder Coating
UV-cured powder coating technology is a rapidly
growing segment of the coatings industry and is emerging
as the answer to rising environmental concerns and
stringent regulations on coating processes. The technology
has lower energy costs, one of the fastest cure speeds,
and offers a reduced environmental impact. These are
just a few reasons why one should strongly consider
using UV-curable powder coating technology.
The electrostatic powder application function of a UVcured
powder coating system and a thermoset powder
coating system are exactly the same. However, the differentiating
characteristic of UV-curable powder coating
is the separation of melt and flow from cure (Figure 1).
This separation enables the processor to control the melt/
flow and cure functions with precision and efficiency,
and helps maximize energy efficiency, improve material
utilization and increase production quality of UV-curable
powder coating systems. Since the
introduction of UV-curable powder
coating, external market conditions
have changed, making the advantages
and benefits even more compelling.
Benefits of UV Powder
UV-curable powder coating is
one of the fastest coating chemistries
available. From start to finish, the
entire process for finishing MDF takes
20 min. or less, depending on chemistry
and part geometry, making it a
suitable finish for applications that
require a quick turnaround. A completed
part requires only one coat, allowing
increased production with 40
to 60 percent less energy than other
finishing processes (Figure 2).
The UV-curing process reduces
throughput times, generating a
number of efficiency benefits such
as less time waiting on daily startup
and shutdown, increased finishing
capacity, a reduced number of parts
on the finishing line, and a reduction
in defects and rework.
The UV powder itself is environmentally
friendly, containing no
solvents, VOCs, HAPs, monomers
or additives, making it safe to use. A
spill can be swept or vacuumed with
no residual damage to equipment
or property. The process also offers
a small carbon footprint. It can be
recycled or repurposed and doesn’t
require operating permits.
Another major benefit of powder
coating is the ability to recapture
sprayed powder and reintroduce it
into the finishing operation. In fact,
powder over-spray is reclaimable
up to 98 percent. UV-curable powder
coatings reduce or eliminate
the material handling, permitting,
environmental and waste disposal
costs associated with the use of liquid
coatings, whether solventborne or
waterborne. They also have better life
cycle advantages than liquid coatings
because solid materials are easier to
blend, process, control and apply
than liquid materials (Figure 3).
UV-curable powder coating offers
a higher-quality finished product
while at the same time reducing substrate
thermal exposure. This is especially
important when finishing MDF
or other novel substrates, as these
materials are sensitive to extended
periods of heat. The coatings can be
formulated to specific products and
are available in a range of color, gloss
and texture (Figure 4).
Because the process is faster and
provides a higher ROI, you can process
more material in a shorter time
period, and the total applied cost is
lower compared to other finishing
systems.
Manufacturers and service providers
are challenged by the demand
for innovative products and services,
and are further challenged to ensure
sustainability throughout the supply
chain. Customers make intentional
and conscious buying decisions
based on criteria and standards
that define products and services as
sustainable. Consumers are actively
seeking materials and processes that
are safe—safe to make, safe to use
and safe to dispose.
Cost Benefits
While UV-curable powder coatings
have numerous advantages over
solventborne and waterborne finishes
from a chemistry standpoint, they
also have advantages from a cost-savings
standpoint. A UV-curable
powder application system can have
a plant footprint of 2,050 sq. ft., as
compared to a solventborne finishing
system of comparable output,
which requires a footprint in excess
of 16,000 sq. ft. Assuming an average rental of $6.50 per
sq. ft. per year, an estimated UV-cure system’s annual cost
would be $13,300 compared to $104,000 for solventborne
(Figure 5).
UV-curable powder coating systems can produce
higher volumes of finished materials, again generating
higher and faster returns on investment. These process
advantages can yield productivity advantages in excess
of 200 percent, demonstrating that the adage “time is
money” is still valid (Figure 6).
Conclusion
With increased awareness of sustainability, efficiency
and safety, UV-curable powder coatings offer numerous
opportunities for future growth. The technology and
process is fast, clean and green. The innovative chemistries
used and the application technologies involved
deliver more value at a lower cost, displacing existing
finishing chemistries and application technologies. Their
significant and compelling features are part of the reason
UV-curable powder coatings and application technologies
are gaining popularity.
Michael Knoblauch is president of Keyland Polymer Ltd.,
Cleveland. He can be reached at mfk@keylandpolymer.com.
